It is known to provide pile guides for underwater piling, see for example, Sea Steel Ltd's range of pile guides as described in WO99/11872 (Fast Frame pile guide), WO01/92645 (Finned Frame/Follower pile guide) and WO03/074795 (Orientation Control pile guide). With such pile guides, piles may be driven into the seabed using hydraulic hammers, such as the IHC Hydrohammers supplied by Dutch Company IHC Hydrohammer BV. However, to date it has not been possible to operate the hammers effectively or economically below about 500 m below sea level for several reasons. If the power supply for the hydraulic hammer is situated at the surface, the length of hydraulic (umbilical) hose required to reach the seabed becomes problematic due to weight and friction losses and required winch capacity for such a hose. If the power supply for the hydraulic hammer is situated at or near the seabed, different problems arise. For example, providing a “girdle” type power supply coupled to the hammer produces an assemblage which is—in practical terms—too large to pass through existing pile guides. Such a power supply is known from U.S. Pat. No. 4,817,734. Also, providing a “container” type power supply which sits independently on the seabed involves additional work during initial deployment, when transferring at seabed, and during subsequent recovery.
The present applicant(s) have sought to address the problems of pile driving at depths in excess of 500 m below sea level, and propose a novel solution which is applicable to underwater pile driving at any depth.